Titanium dioxide is added to some food packaging to preserve the shelf life of a product.

Titanium dioxide can be both safe and unsafe, depending on its use. When inhaled, titanium dioxide is considered possibly carcinogenic to humans. This means that in products that contain powdered titanium dioxide like loose powders, pressed powders, eyeshadows, and blushes in which the makeup is in powder form, titanium dioxide can be inhaled. Titanium dioxide is also an occupational chemical of concern, as workers might inhale titanium dioxide when manufacturing products.

In a study published in the journal Toxicology, researchers examined the effects of exposing human colon cancer cell line (HTC116) titanium dioxide food additives in vitro. “In the absence of cytotoxicity, E171 was accumulated in the cells after 24 hours of exposure, increasing granularity and reactive oxygen species, inducing alterations in the molecular pattern of nucleic acids and lipids, and causing nuclei enlargement, DNA damage and tubulin depolymerization,” the scientists wrote. Researchers removed the additive from the culture, then examined the results 48 hours later. They found, “The removal of E171 was unable to revert the alterations found after 24 h of exposure in colon cells. In conclusion, exposure to E171 causes alterations that cannot be reverted after 48 h if E171 is removed from colon cells.”